Physics

A Fertile Majorana Habitat

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Science  08 Oct 2010:
Vol. 330, Issue 6001, pp. 152
DOI: 10.1126/science.330.6001.152-b

Most species of (near-) elementary particles (such as electrons and protons) have their own antiparticle partners with which they annihilate in a burst of gamma rays. Usually the antiparticle is distinct from the particle. An exotic exception to that rule is the spin-1/2 Majorana fermion, which is its own antiparticle. Although predicted more than 70 years ago, Majorana fermions are yet to be observed, with neutrinos and dark matter WIMPs being the prime candidates. Recently, another possible setting for Majoranas emerged in solid-state materials such as certain topological insulators (TIs) that have a linear electron dispersion but are also superconducting. On doping the TI Bi2Se3 with copper, a superconducting state was observed; however, calculations indicated that such doping would destroy the conditions necessary to support the Majorana state. Now, Wray et al. find in their angle-resolved photoemission experiments that this is not the case, raising a realistic possibility of a first observation of a Majorana fermion.

Nat. Phys. 6, 10.1038/nphys1762 (2010).

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